JP2014119098A - Transmission ratio variable device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission ratio variable device that can reduce variations of preload applied from both sides of a bearing gear with a simple configuration.SOLUTION: A cylindrical preload adjustment plug 79 inserts a communication hole 67 axially brought into communication with the center of an inner ring 65 of a Z1 gear 61, a Z4 gear 62 and a center bearing 63. A male screw part 83 is formed in the circumference of one end of a preload adjustment plug 79, and screwed to a female screw part 84 formed in the inner circumference of a Z1 gear 61. A disc-shaped flange part 82 extended outside in the radial direction is formed in the other end, and axially presses a back face of a Z4 gear 62 through a thrust needle bearing 81. A locknut 80 formed of the female screw part 84 is screwed at the end part of the male screw part 83 with the Z1 gear 61 threadedly attached thereto, and the preload adjustment plug 79 is controlled to become loose. Thereby, the preload adjustment plug 79 is disposed in a predetermined position in the communication hole 67, and a predetermined preload is applied to the engagement part of a bearing gear 25.

Description

  The present invention relates to a transmission ratio variable device.

  Conventionally, a transmission mechanism using a swinging gear has been known. By using a differential mechanism, the rotation of the input shaft based on the steering operation is added to the rotation based on the motor drive and transmitted to the output shaft. A transmission ratio variable device that changes the rotation transmission ratio (steering gear ratio) between input and output shafts has been proposed (see, for example, Patent Document 1).

  The transmission mechanism of such a transmission ratio variable device includes a first gear that rotates integrally with the input shaft, a fourth gear that rotates integrally with the output shaft, a second gear that meshes with the first gear, and a third gear that meshes with the fourth gear. An oscillating gear mechanism having a gear and having an oscillating gear rotating around an axis inclined with respect to the axis of the first and fourth gears is provided as a differential mechanism. The oscillating gear rotates due to the difference in the number of teeth of the first gear and the second gear, and the fourth gear and the third gear, which are engaged with each other while oscillating in the axial direction of the input shaft via the bearing. The input is shifted to the output shaft and transmitted, and the rotation transmission ratio between the input shaft and the output shaft is changed by rotating the oscillating gear using drive means.

JP 2010-13078 A

  In such a transmission ratio variable device, there is a case in which a noise occurs due to a shift in a meshing portion of a swing gear mechanism, a so-called bearing gear (reduction gear). Therefore, in order to mesh at a stable position and suppress abnormal noise, a structure in which the meshing portion of the bearing gear is supported from both sides in the axial direction by the first and fourth gears and a preload (load) is applied to the swing gear side. It is used. For example, by using a method in which a preload plug is fastened and fixed from both sides of the first gear and the fourth gear, preload is applied to the meshing portions of the bearing gear, and the meshing state is maintained well. However, since it is necessary to apply preload to each of the first gear and the fourth gear, the number of manufacturing steps increases, and the performance may vary due to variations in preload on both sides. In addition, since the oscillating gear is interposed between the first gear and the fourth gear, when the bearing gear has low thrust rigidity, the oscillation of the oscillating gear increases and the meshing of the teeth shifts to cause vibration of the bearing gear. Or cause damage.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a transmission ratio variable device that can reduce variations in preload applied from both sides of a bearing gear with a simple configuration.

  In order to solve the above-mentioned problem, a transmission ratio variable device according to claim 1 includes an input shaft coupled to a steering wheel, a housing that supports the input shaft so as to be relatively rotatable, and a motor output with respect to the housing. An electric motor having a shaft that is rotatable relative to the motor, a reduction gear that is connected to the motor output shaft and outputs a turning angle with a reduced motor rotation angle, and the turning angle output from the reduction gear is a steered wheel. An output shaft that transmits to the side of the gear, and a preload applying mechanism that applies an axial preload to the meshing portion of the gear of the speed reducer, the speed reducer being provided so as to be integrally rotatable with the input shaft. A first gear having one tooth; a fourth gear provided on the output shaft so as to be integrally rotatable; and a fourth gear having a fourth tooth formed on an end surface facing the end surface of the first gear; the input shaft; Inclined with respect to the output shaft And the second and second end faces on the different end faces so as to mesh with the first and fourth gears, respectively. A second gear and a third gear formed with three teeth, wherein the first and fourth gears are swung in the axial direction of the input shaft with the rotation of the inclined shaft between the first and fourth gears. An oscillating gear that rotates due to a difference in the number of teeth from the two gears or a difference in the number of teeth from the fourth and third gears, and the preload applying mechanism is formed in a cylindrical shape, and the first gear And the other end portion of the swing gear and the fourth gear are axially inserted through a communication hole communicating with the center of the fourth gear, the other end portion is screwed to the inner peripheral surface of the first gear so as to be axially movable. A flange portion extending radially outward is provided on the back surface of the fourth gear. And summarized in that with a preload adjusting plug coupling.

  According to the above configuration, the cylindrical preload adjusting plug is inserted through the central communication hole of the first gear, the swing gear, and the fourth gear in the axial direction, and one end is axially movable on the inner peripheral surface of the first gear. A flange portion that is screwed and extends radially at the other end is engaged with the back surface of the fourth gear. As a result, the first gear and the fourth gear can be connected with one preload adjusting plug, so that the number of manufacturing steps can be reduced.

  According to a second aspect of the present invention, in the transmission ratio variable device according to the first aspect, the preload adjusting plug can be advanced and retracted in the axial direction by rotation, and the input shaft is moved by moving in the input shaft direction. The gist is that it is biased in a direction approaching the output shaft. According to the above configuration, the first gear and the fourth gear move while being biased toward the swing gear. Thereby, since the preload of the same magnitude | size can be provided to the meshing part of the both sides of a reduction gear with respect to the fastening torque of a preload adjustment plug, the performance of the stable reduction gear can be ensured.

  According to a third aspect of the present invention, in the transmission ratio variable device according to the first or second aspect, the preload applying mechanism is disposed between the first gear and the input shaft, and the preload adjusting plug is connected to the preload adjusting plug. The gist of the invention is that it includes an annular locking nut that is screwed onto the outer peripheral surface of one end of the preload adjusting plug so as to be pressed against the swing gear side. According to the above configuration, the preload adjusting plug is pressed against the axially oscillating gear by the locking nut and is restricted from loosening during operation.

  According to a fourth aspect of the present invention, in the transmission ratio variable device according to any one of the first to third aspects, the preload applying mechanism is provided between the flange portion of the preload adjusting plug and the fourth gear. And a thrust needle bearing that supports the fourth gear so as to be relatively rotatable. According to the above configuration, the rigidity in the thrust direction of the reduction gear can be increased by disposing the thrust needle bearing between the flange portion of the preload adjusting plug and the first gear. As a result, an axial preload is applied to the meshing portion of the speed reducer, and a good meshing state between the gears can be maintained.

  ADVANTAGE OF THE INVENTION According to this invention, the transmission ratio variable apparatus which can reduce the dispersion | variation in the preload provided from the both sides of a bearing gear by simple structure can be provided.

The schematic diagram which shows schematic structure of the steering apparatus for vehicles provided with the transmission ratio variable apparatus which concerns on one Embodiment of this invention. The longitudinal section of the transmission ratio variable device concerning one embodiment of the present invention. The expanded sectional view of the preload provision mechanism in FIG. The perspective view of a preload adjustment plug. The perspective view of a locking nut.

Next, a transmission ratio variable device mounted on a vehicle according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus 1 including a transmission ratio variable device 15 according to an embodiment of the present invention. As shown in FIG. 1, in the vehicle steering apparatus 1, a steering shaft 3 to which a steering wheel 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. Thereby, the rotation of the steering shaft 3 accompanying the steering operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4. The steering shaft 3 is configured by connecting a column shaft 8, an intermediate shaft 9, and a pinion shaft 10.

  The reciprocating linear motion of the rack shaft 5 accompanying the rotation of the steering shaft 3 is transmitted to the knuckle (not shown) via the tie rods 11 connected to both ends of the rack shaft 5, so that the steering angle of the steered wheels 12, that is, The traveling direction of the vehicle is changed. The vehicle steering apparatus 1 according to the present embodiment converts the rotation of the assist motor 13 into a reciprocating linear motion of the rack shaft 5 by the ball screw mechanism 14 and transmits it, thereby using the motor torque as an assist force in the steering system. Is configured as a so-called rack assist type electric power steering device (EPS).

  The vehicle steering apparatus 1 also includes a transmission ratio variable device that varies the ratio of the steering angle (tire angle) of the steered wheels 12 to the steering angle (steering angle) of the steering wheel 2, that is, the transmission ratio (steering gear ratio). 15 is provided in the middle of the column shaft 8. The transmission ratio variable mechanism 15 is for changing the rotation transmission ratio between the input and output shafts of the column shaft 8 of the steering shaft 3, and is a swing gear mechanism.

  FIG. 2 is a longitudinal sectional view of the transmission ratio variable device 15 according to one embodiment of the present invention. As shown in FIG. 2, the transmission ratio variable device 15 includes a substantially cylindrical housing 21 fixed to a vehicle body (not shown) of a car, and a first shaft as an input shaft to which rotation associated with a steering operation is input. (Hereinafter referred to as an input shaft) 22 and a second shaft (hereinafter referred to as an output shaft) 23 as an output shaft connected to the intermediate shaft 9 (see FIG. 1). The input shaft 22 and the output shaft 23 are rotatably supported with respect to the housing 21 via ball bearings 38 and 39 and a needle bearing 70, and constitute the column shaft 8 (see FIG. 1). . That is, the housing 21 is a non-rotating member that does not rotate due to the rotation of the input shaft 22.

  The transmission ratio variable device 15 includes an electric motor 24 housed in the housing 21 and a bearing gear (reduction gear) 25 as a differential mechanism. The transmission ratio variable device 15 uses a bearing gear 25 to add rotation based on motor drive to the rotation of the input shaft 22 and transmit it to the output shaft 23. Furthermore, the transmission ratio variable device 15 includes a lock mechanism 26 that can lock (restrict) the rotation of the electric motor 24 as necessary to mechanically fix the transmission ratio.

  Specifically, the housing 21 is formed of a metal material (for example, an aluminum alloy), and includes a cylindrical housing body 31 in which the electric motor 24 and the bearing gear 25 are accommodated, and one axial end side of the housing body 31 ( An annular lower cover 32 that covers the left side in FIG. 2 (arrow a2 side) is provided. The housing body 31 is formed with a motor housing portion 35 in which the electric motor 24 is housed radially outward and a gear housing portion 36 in which the bearing gear 25 is housed radially inward.

  A lock mechanism 26 that locks the motor rotation shaft (motor output shaft) 45 is housed in the other axial end side of the housing body 31 (right side in FIG. 2: arrow a1 side). The input shaft 22 is rotatably supported by a needle bearing 70 provided at the bottom of the housing body 31, and the output shaft 23 is rotatably supported by ball bearings 38 and 39 provided on the lower cover 32. In addition, the input shaft 22 and the output shaft 23 are mutually coaxially arrange | positioned (axis line L1).

  The electric motor 24 is configured as a brushless motor including a stator 41 that is fixed in the motor housing portion 35 and a rotor 42 that is rotatably provided inside the stator 41. The motor rotation shaft 45 is formed in a hollow shape, and the input shaft 22 is coaxially inserted into the motor rotation shaft 45. Further, the axial length of the motor rotating shaft 45 is set to be longer than the axial length of the motor housing portion 35, and the shaft end on the arrow a <b> 1 side is disposed in the housing body 31, and the arrow The shaft end portion on the a2 side is disposed in the gear housing portion 36. The motor rotation shaft 45 is rotatably supported by a ball bearing 48 provided on the lower cover 32 and a ball bearing 49 provided on the housing body 31. Further, a rotation angle sensor (not shown, for example, a resolver) that detects the rotation angle of the rotor 42 is accommodated in the motor accommodating portion 35 of the housing body 31.

  In the present embodiment, by housing the bearing gear 25 inside the rotor 42, the length of the housing 21 in the axial direction can be shortened. As a result, a long shock absorbing stroke of the vehicle can be secured, or the housing 21 It is possible to secure a mounting space for other devices (for example, a tilt / telescopic mechanism) that are mounted adjacent to each other.

  As shown in FIG. 2, an inclined shaft portion 53 is connected to the inner side in the radial direction of the motor rotation shaft 45 so as to be integrally rotatable. The inclined shaft portion 53 has an axis L2 that is inclined with respect to the axis L1 of the motor rotation shaft 45 (the axis of the input shaft 22 and the output shaft 23). The outer peripheral surface of the inclined shaft portion 53 has a cylindrical shape that is inclined with respect to the axis L1.

  The bearing gear 25 includes a Z1 gear (first gear) 61 coupled to the input shaft 22 so as to be integrally rotatable, a Z4 gear (fourth gear) 62 coupled to the output shaft 23 so as to be integrally rotatable, and a Z1 gear 61. And a Z4 gear 62, and a center bearing (oscillating gear) 63 connected to the motor rotating shaft 45 via the inclined shaft portion 53.

  Specifically, the Z1 gear 61 is formed in a cylindrical shape, and a plurality of first teeth protruding toward the arrow a2 side are provided along the circumferential direction on the outer peripheral edge of the Z1 gear 61. In the present embodiment, each first tooth is constituted by cylindrical rollers that are arranged radially with respect to the Z1 gear 61 and are arranged so as to be rotatable around the axis thereof. Further, the Z1 gear 61 is connected to the input shaft 22 so as to be rotatable integrally with the input shaft 22 by the serration fitting of the shaft end portion of the input shaft 22 to the inner peripheral surface. That is, the axis of the Z1 gear 61 coincides with the axis L1 of the motor rotation shaft 45.

  The Z4 gear 62 is formed in a disk shape, and the Z4 gear 62 is provided with a plurality of fourth teeth that protrude in the direction of the arrow a1 in the circumferential direction. In addition, in this embodiment, each 4th tooth | gear is comprised by the cylindrical roller arrange | positioned so that it can rotate to the periphery of the axis line similarly to the Z1 gear 64, and is arrange | positioned radially with respect to the Z4 gear 62. Yes. The Z4 gear 62 is fixed to the inner periphery of the motor rotating shaft 45 formed in a cylindrical shape, and is serrated and connected to the outer peripheral surface of the output shaft 23. In other words, the Z4 gear 62 is connected to the output shaft 23 so as to be rotatable integrally therewith, and the axis of the Z4 gear 62 coincides with the axis L1 of the motor rotation shaft 45. Ball bearings 68 and 69 are interposed between the inclined shaft portion 53 and the Z1 gear 61 and the Z4 gear 62, respectively.

  The center bearing 63 includes a cylindrical outer ring 64, a cylindrical inner ring gear 65, and rolling elements (balls) 66 interposed between the outer ring 64 and the inner ring gear 65. On the end surface of the inner ring gear 65 on the arrow a1 side (Z1 gear 61 side), a plurality of second teeth that can mesh with the first teeth are provided side by side in the circumferential direction. On the other hand, on the end surface of the inner ring gear 65 on the arrow a2 side (Z4 gear 62 side), a plurality of third teeth that can mesh with the fourth teeth are provided side by side in the circumferential direction. That is, the inner ring gear 65 constitutes a Z2 gear (second gear) 76 and a Z3 gear (third gear) 77. In the present embodiment, the number N1 of the first teeth is set to be one less than the number N2 of the second teeth, and the number N3 of the third teeth is equal to the number N4 of the fourth teeth. It is set to the same number. For example, when the number of teeth N1 = 19, the number of teeth N2 = 20, the number of teeth N3 = 20, and the number of teeth N4 = 20, the reduction ratio R between the motor rotation shaft 45 and the output shaft 23 at this stage is set to 20. ing.

  The outer ring 64 is connected to the outer periphery of the inclined shaft portion 53 so as to be integrally rotatable with the motor rotating shaft 45. That is, the axis of the center bearing 63 coincides with the axis L2 of the inclined shaft portion 53, and the center bearing 63 rotates around the axis inclined with respect to the axes of the Z1 and Z4 gears 61 and 62. In the inner ring gear 65, only a part of the Z2 gear 76 meshes with the Z1 gear 61, and only a part of the Z3 gear 77 meshes with the Z4 gear 62. Note that the meshing portion between the Z1 gear 61 and the Z2 gear 76 and the meshing portion between the Z4 gear 62 and the Z3 gear 77 are separated from each other by about 180 ° with the axes of the Z1 and Z4 gears 61 and 62 as the center.

  The bearing gear 25 is preloaded in the axial direction by the preload applying mechanism 78 so that the Z1 gear 61 and the Z4 gear 62 are close to each other. The preload applying mechanism 78 is configured such that the preload adjusting plug 79 screwed to the inner peripheral surface of the Z1 gear 61 connected to the input shaft 22 is rotationally moved by being tightened from the outside, whereby the Z1 gears 61 and Z4 are axially moved. The gear 62 is configured to be urged so that the axial preload applied to the center bearing 25 can be adjusted and maintained.

  As described above, in the bearing gear 25 in which the input shaft 22, the output shaft 23, and the motor rotation shaft 45 are respectively connected, the rotation of the input shaft 22 is transmitted from the Z1 gear 61 through the center bearing 63 through the Z4 gear 62. It is transmitted to the output shaft 23. Further, when the electric motor 24 is driven and the motor rotation shaft 45 rotates, the inclined shaft portion 53 connected to the motor rotation shaft 45 performs an eccentric motion (swing motion). As a result, the inner ring gear 65 moves eccentrically with the outer ring 64 fixed to the inclined shaft part 53, and the meshing part of the Z1 gear 61 and the Z2 gear 76 and the meshing part of the Z4 gear 62 and the Z3 gear 77 are in the same direction. Rotate.

  As a result, the rotation difference based on the number of teeth difference between the Z1 gear 61 and the Z2 gear 76 and the Z4 gear 62 and the Z3 gear 77 is added to the input shaft 22 as a rotation based on the motor drive and transmitted to the output shaft 23. (For example, when the reduction ratio R is 20, the output shaft 23 is added by one rotation per 20 rotations of the motor rotation shaft 45). Therefore, the rotation transmission ratio between the input shaft 22 and the output shaft 23 according to the rotation based on the motor drive, that is, the transmission ratio between the steering wheel 2 (see FIG. 1) and the steered wheels 12 (see FIG. 1) ( Steering gear ratio) is changed.

  3 is an enlarged sectional view of the preload applying mechanism 78 in FIG. 2, FIG. 4 is a perspective view of the preload adjusting plug 79, and FIG. 5 is a perspective view of a lock nut (loosening prevention nut) 80. As shown in FIG. 3, the Z1 gear 61, the Z4 gear 62 of the transmission ratio variable mechanism 15 (see FIG. 2), and the inner ring gear 65 of the center bearing 63 each have an annular shape. One end of the input shaft 22 is connected to the Z1 gear 61 so as to be integrally rotatable by being inserted through the inner periphery of the Z1 gear 61. The output shaft 23 is connected to the Z4 gear 62 so as to be integrally rotatable by being inserted through the inner periphery of the Z4 gear 62.

  The preload applying mechanism 78 includes a preload adjusting plug 79, a thrust needle bearing 81, and a lock nut 80. A cylindrical preload adjusting plug 79 is inserted through a communication hole 67 that communicates the center of the Z1 gear 61, the Z4 gear 62, and the inner ring gear 65 of the center bearing 63 in the axial direction. A male screw portion 83 is formed on the outer periphery of one end of the preload adjusting plug 79 and is screwed to a female screw portion 84 formed on the inner periphery of the Z1 gear 61. In addition, a disk-shaped flange portion 82 extending radially outward is formed at the other end of the preload adjusting plug 79, and the back surface of the Z4 gear 62 is pressed in the axial direction via the thrust needle bearing 81. . An annular lock nut 80 having an internal thread portion 84 formed on the inner periphery thereof is screwed to the end of the external thread portion 83 of the preload adjustment plug 79 to which the Z1 gear 61 is screwed, so that the preload adjustment plug 79 is loosened. It is regulated. Accordingly, the preload adjusting plug 79 is disposed at a predetermined position in the communication hole 67 and applies a predetermined preload to the meshing portion of the bearing gear 25 in the axial direction.

  Further, as shown in FIGS. 4 and 5, a through hole 85 is formed in the center of each of the preload adjusting plug 79 and the lock nut 80 in the axial direction. The through-hole 85 has a hollow shape (for example, a hexagonal shape) that can rotate the preload adjusting plug 79 and the lock nut 80 when a tool (not shown) is engaged in the circumferential direction from the outside.

Next, the preload adjustment work of the preload applying mechanism 78 of this embodiment will be described.
After the bearing gear 25 is assembled, the thrust needle bearing 81 is assembled, the preload adjusting plug 79 is inserted into the communication hole 85, and the male screw portion 83 at one end is screwed to the female screw portion 84 on the inner peripheral surface of the Z1 gear 61. Subsequently, the tool is inserted into the hexagonal through hole 85 on the inner diameter side of the preload adjusting plug 79 from the output shaft 23 side, and the preload adjusting plug 79 is rotated with a predetermined tightening torque. As a result, the preload adjusting plug 79 moves to a predetermined position regardless of an assembly error or the like, and a preload is applied to the bearing gear 25. Next, the female screw portion 84 of the lock nut 80 is screwed into the male screw portion 83 of the preload adjusting plug 79, the tool is inserted into the hexagonal through hole 85 of the lock nut 80 from the input shaft 22 side, and the lock nut 80 is rotated. tighten. As a result, the male screw portion 83 and the female screw portion 84 are in close contact with each other to close the gap, and the loosening of the preload adjusting plug 79 is restricted.

  Next, the operation and effect of the transmission ratio variable device 15 according to the present embodiment configured as described above will be described.

  According to the above configuration, the cylindrical preload adjusting plug 79 is inserted through the center of the Z1 gear 61, the center bearing 63 and the Z4 gear 62 in the axial direction, and one end thereof is movable in the axial direction on the inner peripheral surface of the Z1 gear 61. A flange portion 82 that is screwed and extends radially outward to the other end is engaged with the back surface of the Z4 gear 62. When the preload adjusting plug 79 is tightened by the rotation of the preload adjusting plug 79 and moves in the direction of the input shaft 22, the Z1 gear 61 and the Z4 gear 62 move while being biased toward the center bearing 63 side. The preload adjusting plug 79 is pressed against the axial center bearing 63 side by an annular lock nut 80 screwed to the male threaded portion 83 at one end and is restricted from loosening during operation.

  A thrust needle bearing 81 is disposed between the flange portion 82 of the preload adjusting plug 79 and the back surface of the Z4 gear 62. The thrust needle bearing 81 can increase the rigidity in the thrust direction, and can suppress the meshing of the teeth of the bearing gear 25 due to an impact. The preload adjusting plug 79 applies a predetermined preload to the bearing gear 25 by the flange portion 82 directly pressing the Z4 gear 62 via the thrust needle bearing 81.

  As a result, the preload applying mechanism 78 does not include an elastic member such as a wave washer, and the preload adjusting plug 79 directly presses the Z4 gear 62 so that the Z1 gear 61 and the Z4 gear 62 are brought closer to each other. A predetermined axial preload is applied to the 25 meshing portions, and a good meshing state between the gears can be maintained. Further, since the Z1 gear 61 and the Z4 gear 62 can be connected by one preload adjusting plug 79, the manufacturing process can be reduced, and both sides of the bearing gear 25 with respect to the tightening torque of the preload adjusting plug 79 can be reduced. The preload of the same magnitude | size can be provided to the meshing part. As a result, even if there is an assembly error or the like, the preload applied from both sides to the fitting portion of the bearing gear 25 is reduced, and stable performance of the bearing gear 25 can be obtained.

  As described above, according to the embodiment of the present invention, it is possible to provide a transmission ratio variable device that can reduce variations in preload applied from both sides of the bearing gear with a simple configuration.

  As mentioned above, although embodiment which concerns on this invention was described, this invention can also be implemented with another form.

  In the above embodiment, the preload adjusting plug 79 is screwed to the input shaft 22 and tightened to urge the Z1 gear 61 to apply the preload to the bearing gear 25. However, the present invention is not limited to this. A preload adjusting plug 79 may be provided to urge the Z4 gear 62 to apply a preload to the bearing gear 25.

  In the above embodiment, the present invention is applied to the transmission ratio variable device 15 in which the housing 21 does not rotate due to the rotation of the input shaft 22. However, the present invention is not limited to this. You may apply to a ratio variable apparatus. The housing 21 may be disposed so as to surround the intermediate shaft 8 or may be disposed in the engine room of the vehicle. In the above embodiment, the steering wheel 2 may be coupled to the output shaft 23 side, and the intermediate shaft 9 may be coupled to the input shaft 22. That is, the input shaft 22 may be the output shaft and the output shaft 23 may be the input shaft.

  In the above embodiment, the outer ring gear of the center bearing 63 may connect the Z1 gear 61 and the Z4 gear 62 so as to be differentially rotatable, and the inner ring may be connected to the rotor 42 of the electric motor 24 so as to be integrally rotatable. .

  In the above embodiment, the rolling element 66 may be a cylindrical roller, a needle roller, or a tapered roller. Further, it may be a single row or a double row. When double rows are used, the inner ring gear 65 can be prevented from falling. For example, a double row angular bearing is used as the double row.

  In the above-described embodiment, the present invention is applied to the bearing gear type transmission ratio variable device 15. However, the present invention is not limited to this, and may be applied to a wave gear type transmission ratio variable device. Further, the present invention is not limited to the column mounting type, and may be applied to an intermediate (intermediate shaft) mounting type or a pinion gear integrated type transmission ratio variable device.

  In the above-described embodiment, the present invention is applied to the transmission ratio variable device 15 of the vehicle steering device 1, but can be applied to other general devices used for other purposes. In addition, the vehicle steering device 1 is configured as a rack assist type electric power steering device including a steering assist mechanism that applies a motor assist force to the steering shaft 3, but is not limited thereto, and the column assist type or the pinion assist type. The electric power steering apparatus may be used, or the steering assist mechanism may be eliminated.

1: vehicle steering device, 2: steering wheel, 3: steering shaft, 4: rack and pinion mechanism, 5: rack shaft, 8: column shaft, 9: intermediate shaft, 10: pinion shaft, 11: tie rod, 12: Steered wheel, 13: assist motor, 14: ball screw mechanism,
15: transmission ratio variable device, 21, 31, 32: housing, 22: input shaft, 23: output shaft, 24: electric motor, 25: bearing gear (reduction gear), 26: lock mechanism, 35: motor housing, 36: gear housing portion, 38, 39, 48, 49, 68, 69: ball bearing, 41: stator, 42: rotor, 45: motor rotating shaft (motor output shaft), 53: inclined shaft portion,
61: Z1 gear (first gear), 62: Z4 gear (fourth gear), 63: center bearing (oscillating gear), 64: outer ring, 65: inner ring gear, 66: rolling element, 67: communication hole, 70 : Needle bearing, 76: Z2 gear (second gear), 77: Z3 gear (third gear), 78: Preloading mechanism, 79: Preload adjusting plug, 80: Lock nut (loosening prevention nut), 81: Thrust needle Bearing, 82: flange portion, 83: male screw portion, 84: female screw portion, 85: through hole,
N1 to N4: number of teeth, L1, L2: axial center, R: reduction ratio

Claims (4)

An input shaft coupled to the steering wheel;
A housing that supports the input shaft in a relatively rotatable manner;
An electric motor provided with a motor output shaft that can rotate relative to the housing;
A reduction gear connected to the motor output shaft and outputting a turning angle with a reduced motor rotation angle;
An output shaft that transmits the steered angle output from the speed reducer to the steered wheels;
A preload application mechanism that applies an axial preload to the meshing portion of the gear of the speed reducer,
The speed reducer is
A first gear provided on the input shaft so as to be integrally rotatable and having first teeth formed on an end surface;
A fourth gear provided on the output shaft so as to be integrally rotatable, and having a fourth tooth formed on an end surface facing the end surface of the first gear;
An inclined shaft provided to be inclined with respect to the input shaft and the output shaft;
Inclined with respect to the motor output shaft and supported so as to be rotatable relative to the inclined shaft, and second and third teeth are formed on different end faces so as to mesh with the first and fourth gears, respectively. There are a second gear and a third gear, and the number of teeth of the first and second gears while the input shaft is swung in the axial direction with the rotation of the inclined shaft between the first and fourth gears. Or a rocking gear that rotates by the difference in the number of teeth of the fourth and third gears,
The preload applying mechanism is formed in a cylindrical shape, and is inserted in an axial direction through a communication hole that communicates with the center of the first gear, the swing gear, and the fourth gear, and one end portion is an inner periphery of the first gear. A preload adjusting plug that is screwed to the surface so as to be axially movable and that has a flange portion that extends radially outward at the other end to engage the back surface of the fourth gear. Transmission ratio variable device. The transmission ratio variable device according to claim 1,
The preload adjusting plug is capable of moving back and forth in the axial direction by rotation, and biasing the input shaft in a direction approaching the output shaft by moving in the input shaft direction. . The transmission ratio variable device according to claim 1 or 2,
The preload applying mechanism is disposed between the first gear and the input shaft, and is screwed onto an outer peripheral surface of one end of the preload adjusting plug so as to press the preload adjusting plug against the swinging gear. A variable transmission ratio device comprising an annular locking nut. The transmission ratio variable device according to any one of claims 1 to 3,
The preload applying mechanism includes a thrust needle bearing that is disposed between the flange portion of the preload adjusting plug and the fourth gear and supports the fourth gear so as to be relatively rotatable. Variable device.

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